RHESSI

List all RHESSI datasets

Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI)

Mission Descriptions

Overview

RHESSI (Reuven Ramaty High Energy Solar Spectroscopic Imager) is a NASA solar observation satellite primarily aimed at observing high-energy phenomena on the Sun. It was launched on February 5, 2002, and operated for 16 years until its mission concluded on August 16, 2018, due to aging equipment. The primary scientific objectives of RHESSI are:

  • Understanding impulsive energy releases.
  • Elucidating particle acceleration mechanisms.
  • Studying particle and energy transport processes.

The satellite, including fuel, weighs 293 kg and has a cylindrical shape measuring 2.2 meters in height and 1 meter in width, with four solar panels. It orbited the Earth at a speed of 96.5 minutes per orbit, with a periapsis altitude of 579 km, an apoapsis altitude of 607 km, and an inclination of 38 degrees.

Observation Instruments

Imaging Spectrometer

RHESSI's primary observation instrument is the Imaging Spectrometer, which observes solar flares in the energy range from soft X-rays (~3 keV) to gamma rays (~20 MeV). This instrument combines two key technologies to provide detailed energy spectra and high-resolution images:

  1. Fine Grids: This technology uses fine grids made of tungsten or molybdenum to modulate solar radiation as the spacecraft rotates at about 15 revolutions per minute. This method allows capturing up to 20 detailed images per second, tracking the movement of electrons from their acceleration sites to the lower solar atmosphere.

  2. Germanium Detectors: Utilizing cooled germanium crystals, this technology accurately detects X-ray and gamma-ray photons in the energy range of 3 keV to 20 MeV. This enables detailed characterization of the X-ray and gamma-ray spectra, providing insights into electron and ion acceleration processes.

Achievements

The RHESSI mission provided critical insights into particle acceleration and energy release mechanisms in solar flares through its unique observation capabilities. Key achievements include:

  • Detailed mapping of the spatial distribution and energy spectra of high-energy electrons released during solar flares.
  • New understanding of particle acceleration processes and locations, as well as their energy characteristics.
  • Detailed studies of magnetic fields and electromagnetic processes in the solar atmosphere.

RHESSI's observational data, combined with data from ground-based telescopes and other space probes, has significantly enhanced the comprehensive understanding of the physical environment of solar flares.

Refereneces